Thermally insulating composite frame members for windows, curtainwalls, storefront framing systems, and the like are known wherein elongated inner and outer frame members are structurally interconnected by a thermal isolator. For example, U.S. Pat. No. 4,672,784 to Pohlar discloses a framing structure in which an interior or gutter section is structurally connected to an exterior or face section by connecting clips provided at spaced intervals. The connecting clips include jaw-like end clamps that engage flanges on the gutter and face sections to form a unitary structure. In addition to interconnecting the gutter and face sections, the connecting clips are comprised of thermally insulating material so as to thermally isolate the gutter from the face.
U.S. Pat. No. 4,750,310 to Holcombe discloses a thermally insulating framing system comprising inner and outer spaced-apart frame members structurally interconnected by a thermally isolating clip. One end of the clip comprises a flat base which twist locks into a channel formed on one frame member. The opposite end of the clip comprises a pair of spring legs which engage a cooperating flange on the other frame member.
The connecting clip arrangements in the aforesaid U.S. Pat. Nos. 4,672,784 and 4,750,310 suffer certain disadvantages, in that the use of discrete clips creates gaps between the inner and outer frame members such that no weathertight seal is created. Further, longitudinal shear strength of these structures is suboptimal. Since resistance of the composite frame member to bending is directly related to the longitudinal shear strength of the connection between the inner and outer frame elements, resistance to bending is also suboptimal.
Thus there is a need for a thermally insulating composite frame member for windows, curtainwalls, storefront framing systems, and the like which provides a weathertight seal between the interior and exterior frame members.
There is a further need for a thermally insulating composite frame member for windows, curtainwalls, storefront framing systems, and the like which provides improved longitudinal shear strength and resistance to bending.
U.S. Pat. No. 4,786,539 to Grether discloses a thermal insulating composite laminate in which a pair of spaced-apart metal frame members are interconnected by a pair of thermal insulating bars. Transverse anchoring strips on the synthetic bars are pressed into longitudinally extending grooves on the metal frame members. Deformable tabs formed on the frame members adjacent the longitudinal grooves are bent to ensure locking of the synthetic bars in place.
European Patent Application Serial No. 0 043 968 to Trier discloses a thermally insulating frame member in which inner and outer frame members in parallel, spaced-apart relation are structurally interconnected by a pair of insulating strips. Various embodiments of the insulating strips include either transverse flanges which engage corresponding structure on the respective frame members, or enlarged head portions which interlock with inversely-tapered longitudinal channels formed on mutually facing portions of each of the frame members.
European Patent Application Serial No. 0 085 410 to Ensinger also discloses a thermally insulating frame member in which inner and outer frame members in parallel, spaced-apart relation are structurally interconnected by a pair of insulating strips. The insulating strips are shaped in cross section like a "dog bone" in that they have enlarged portions on opposite sides. These enlarged head portions interlock with inversely-tapered longitudinal channels formed on mutually facing portions of each of the frame members.
The thermally insulating frame members disclosed in the aforesaid U.S. Pat. No. 4,786,539 and European Patent Applications Serial No. 0 043 968 and 0 085 410 suffer certain disadvantages in that the thermal insulator is comprised of two separate components, which increases handling during manufacture and also increases inventory requirements. In addition, the insulating strips used in the frame member of European Patent Application Serial No. 0 085 410 must be longitudinally slid into their respective longitudinal channels during manufacture. Consequently, it is not possible to employ adhesive or other chemical bond to enhance longitudinal shear strength.
Thus there is a need for a thermally insulating composite frame member for windows, curtainwalls, storefront framing systems, and the like which reduces the number of components so as to minimize handling during manufacture and to minimize inventory requirements.
There is a further need for a thermally insulating composite frame member for windows, curtainwalls, storefront framing systems, and the like which permits the use of adhesives to enhance longitudinal shear strength.